My Shapeoko 3 is not cutting on the toolpath

[bikeopelli (dave)]

I purchased my Shapeoko several years ago. Set it up and have been using it (occasionally) with no problems. Recently I fired it up to make some simple parts from .230 plywood, but the dimensions of the resulting parts were not right. So after insuring all the V wheels were properly adjusted, I defined a 1" square and cut 2 of them. One specifying “Cut outside the path” and one specifying “Cut inside the path”. When cutting outside, the resulting square was .035 too short on both sides. When cutting inside, the ‘hole’ was .035 too big on both sides.
I had been using Create 743 and motion 566. Just upgraded to: Create 778 and motion 640. Same results for both.
I am out of ideas.

[WillAdams (William Adams (Carbide 3D))]

Post your files and photos?

Are you cutting a slot just as narrow as the tool? Try offsetting by endmill diameter and cutting as a pocket down to tab height? Leaving a roughing clearance and then taking a finishing pass?

Where possible avoid slotting and add geometry and cut as a pocket

Making vacuum hose adapters

While cutting up vacuum extension wands for this is expedient, it’s a bit problematic given that Shop Vac recently filed for bankruptcy, was bought at the last minute, and production hasn’t caught up. I need a receptacle for the Sweepy 2.0 dust fitting — one option would be to purchase one from Woodcraft, but Carbide 3D sells blocks of HDPE: which looks to be just barely big enough for things to fit. Measuring the hose fitting I get a diameter of ~63.5mm — offsetting that twice we arrive at…

and/or

Adding geometry to cut as a pocket with a finishing pass

One technique which is often suggested to avoid slotting is to add geometry around a part which one wishes to cut out and cut as a pocket down to tab depth — here’s one technique for that. In this case, the project is a bevel gauge which will be cut out of 0.0625" (~1.5mm) thick aluminum: [bevelgauge] Due to the narrowness of the angles, an 0.03125" endmill has to be used, so after importing and scaling the file (we will be cutting out one which is 3") we select the perimeter and offset it tw…

and consider leaving a roughing clearance and taking a finishing pass.

Best Bit for full cut through

One which has a cutting flute length equal to or greater than the thickness of the stock — pretty much any tool should work. Big thing is the toolpaths — if cutting out, rather than just cutting a slot: [image] Offset to the outside by endmill diameter plus 10% or so: [image] [image] [image] Then cut as a pocket: [image] down to tab height or the penultimate pass: [image] then move the contour down to below the pocket and start cutting at the bottom of the pocket: [image] and…

[bikeopelli (dave)]

@WillAdams

Are you cutting a slot just as narrow as the tool?

I am not cutting a slot. As stated… for my test, I am cutting a 1" Square. I did fail to mention I am using an 1/8" bit.

[Redlander (Tim Jones)]

@bikeopelli

Can you upload the test file for the 1’ squares for us to review?

[bikeopelli (dave)]

Thanks for responding. In the event, I solved the problem. Well… sort of.
Since my original post I had tried several things. Everything I could think of even if it really didn’t seem like it might make a difference. No joy. Then it occurred to me to slow everything down and give that a try. Bingo!. Turns out that a feed rate of 20 and my router on the slowest speed solved the problem. What I don’t really understand is… for a long time I have been using higher feed rates and higher rpm and never seem to have this problem. Could it have something to do with vibration at higher rpm’s? Just dunno. In any case its working near perfectly now so that means “Case Closed!”.

[Redlander (Tim Jones)]

@bikeopelli

Sounds like you didn’t solve the problem, you’re just compensating for it and now your projects will take longer to cut?

[WillAdams (William Adams (Carbide 3D))]

Worn tool or some other issue?

To rebuild a machine to pretty much like new see:

Shapeoko Maintenance Kit

[bikeopelli (dave)]

I’m retired… don’t care how long it take s